(a) Field of the Invention
The present invention relates to an apparatus and a method for controlling a vehicle having a motor, and more particularly, to an apparatus and a method for controlling a vehicle having a motor capable of preventing the vehicle from rattling when an antilock brake system (ABS) is operated during regenerative braking.
(b) Description of the Related Art
Generally, an electric vehicle is a type of vehicle which may be driven using a power supply of a battery and may include a pure electric vehicle driven using the power supply of the battery and a hybrid electric vehicle using both of a traditional internal combustion engine and the power supply of the battery. The pure electric vehicle is driven by power of a driving motor operated by the power supply of the battery and the hybrid electric vehicle is driven by an efficient combination of the power of the internal combustion engine and the power of the driving motor.
Further, the hybrid electric vehicle is driven by the power of the motor and the engine and includes a starter and generator configured to start an engine or generate electricity by an output of the engine. In the vehicle having the motor like the pure electric vehicle and the hybrid electric vehicle, the motor and/or the starter and generator are operated as a generator to recover inertial energy upon coasting which drives the vehicle by inertia. When the motor is operated as the generator to recover inertial energy, the braking of the corresponding vehicle is required.
In other words, the inertial energy may be recovered as power generation power by setting a coasting torque (e.g., torque in an opposite direction to a driving direction or coast regeneration torque) based on a vehicle speed in the motor upon the coasting. Particularly, the braking is required. Further, in a hydraulic brake of a general vehicle, a braking hydraulic pressure is applied to a wheel by an operation of a brake pedal, to perform the braking. When a braking force greater than a static friction force between a road surface and a tire is applied to the tire, a slip phenomenon in which the tire slides on the road surface occurs.
Since a kinetic friction coefficient is less than the static friction coefficient, the slip phenomenon should be prevented to implement the optimal braking. Further, a handle locking phenomenon should be prevented upon the operation of the brake due to the slip phenomenon. Therefore, an antilock brake system (ABS) has been used to prevent the slip phenomenon or the handle locking phenomenon from occurring and secure the stabilized braking force, by adjusting the braking hydraulic pressure applied to hydraulic pressure brakes of each wheel.
The ABS includes hydraulic pressure control apparatuses such as a plurality of solenoid valves, an accumulator, and a hydraulic pressure pump configured to adjust the braking hydraulic pressure transferred to each hydraulic pressure brake side and an electric controller (ECU) configured to operate the various electric/electronic components. The ABS is configured to reduce, maintain, or increase the braking hydraulic pressure by sensing a slip of a wheel occurring due to rapid braking of the vehicle or a brake operation on a slide surface, thereby securing an appropriate cornering force and stopping the vehicle at a shortest distance while maintaining steering stability.
Meanwhile, like a general vehicle, the ABS apparatus has been used even in the electric vehicle using the motor as the driving source or the hybrid vehicle using the motor and the engine as the driving source. Generally, the latest trend is to greatly set the coast regeneration torque to increase an energy recovery rate when the vehicle is coasting. However, when a friction coefficient of a road such as a snowy road, an icy road, and a rainy road is minimal, the slip may occur in the driving wheel due to the coast regeneration torque. The driving stability of the vehicle may deteriorate due to the slip. Accordingly, when the slip occurs in the driving wheel due to the coast regeneration torque and thus the ABS is operated, the coast regeneration torque is set to be “0”. However, since the operation and the non-operation of the ABS are repeatedly generated, the control method may cause the coast regeneration torque to be repeatedly applied or may not be applied. Therefore, rattling of the vehicle may occur.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.